Machine to Machine (M2M) is a technology that supports wired or wireless communication between devices, and wireless M2M is applicable to all wireless network technologies such as GSM, GPRS, UMTS and LTE. Examples of the use of M2M communication include sensor networks (for example, networks for monitoring weather conditions), surveillance equipment (for example alarm systems or video monitoring), vehicle fleet management, vending machines, and monitoring manufacturing.
An M2M device is typically provided with a SIM card, and uses the Internet Protocol (IP) for communicating with other devices, allowing for example utility companies to automatically read utility meters, which eliminates the need for personnel to visit customer premises and manually read meters. M2M communications may also be used e.g. for alarm reporting and remote control applications.
In order for the M2M device to communicate via IP with other devices in the cellular network, the M2M device attaches to the network and establishes a PDP (Package Data Protocol) context. Generally, a PDP context is the term used in the 3GPP (Third Generation Partnership Project) when IP connectivity is established between a node comprising a SIM card, e.g. an M2M device or a mobile telephone, and a 3GPP connectivity node, e.g. a GGSN node.
It is predicted that in the long term future, there may be billions of M2M devices, and that the number of M2M devices could exceed the number of mobile telephones and personal computers.
The wide scale introduction of M2M devices in mobile networks will change network traffic profiles and traffic volumes and there is a risk to overload the network. In order to avoid overload, the M2M devices could e.g. exchange data with the cellular network only for a predetermined period, or at a specific time and date. Thereby, the M2M devices could sit silently for potentially long periods, wake up for sending data, and then go back to sleep mode.
However, when an M2M device enters sleep mode, it releases the PDP context and it is no longer reachable via IP (Internet Protocol) communication. This leads to that IP devices are not able to send any messages to an M2M device being in sleep mode.
Hereinafter, the above-described M2M Device will be referred to as an M2M Unit.